Some sites let you disable SMS but still require a TOTP app as a backup option. So sites adopting this model make FIDO kind of pointless. A FIDO option is nice but a determined attacker will just attack the weakest point, which is the SMS backup code. There have also been several low tech attacks on SMS, like tricking a carrier into porting a number to an attacker’s SIM. A security key is a nice option but SMS codes can be stolen and SIMs can be cloned. Many sites still force you to have SMS as an alternate factor. Unfortunately a good number of sites only support Yubikeys so they might be worth the extra money because they are the most supported. Yubikey was my first choice but I did not want to pay the Yubikey price and did not need some of the extra features. I ended up buying the Feitian ePass FIDO-NFC Security Key because it did exactly what I needed and did not cost too much. That said, it has been an overall positive experience.

Unfortunately it didn't work out like I expected. I have recently purchased some FIDO U2F keys and have attempted to do two factor that right way.

Fido u2f